Applying the ISA88 Model to Clean In Place Operations

Every industry has its special jargon that is like a secret handshake. If you’re an insider, you can quickly spot the outsiders based upon their understanding of your industry’s jargon and acronyms. For instance, my background was in the offshore oil and gas business back in the mid ’80s. We had jargon like pigging (to clean out pipes) and Christmas trees (fittings and valves on the top of well casing which control the well production rate) to name a few.

Clean-in-place (CIP) is a method of cleaning vessels and lines without disassembling them. It involves delivering solutions of chemical detergents and rinses at specified flow rates and temperatures. Typically, a CIP skid creates the cleaning solutions and routes them to a user skid that requires cleaning.

According to Christie and Yogesh, CIP began in the 1950s as a manual operation. Over time, this process has been largely automated by most food & beverage, pharmaceutical and cosmetic manufacturers. The authors note that many common challenges exist whether CIP is performed manually or automatically. They include:

Performing similar actions (acid wash, alkali wash) in an efficient way

Managing CIP timing of available resources like process skids, and supply/return piping paths

For processes with portable CIP skids used in multi-product facilities, providing local control and easy point-of-use connects

Christie and Yogesh describe how the ISA88 (often referred to as S88) standard and terminology for batch control are applied to CIP processes to address these common challenges. The ISA88 model is comprised of both a physical and procedural model.

On the physical model side, one recommendation was to make the distribution headers and/or transfer panels into equipment modules that are independent of the CIP skid and the equipment it connects to in order to clean and sterilize. The path can be managed as a resource, which allows CIP skids to operate in a similar fashion.

The authors pointed out that the physical model helps to drive the procedural model. They wrote:

The sequences that operate the CIP skid equipment become phases on the CIP skid unit, and the sequences that operate on the user skid become phases on the user skid unit. Similar sequences can be modularized or made into reusable, flexible phases. The differences are handled with recipe parameters.

A final key point is that the ISA88 procedural model can be optimized to run phases in parallel to reduce the overall CIP cycle time for processes with fixed CIP skids. Their example:

…while circulating the pre-rinse solution from one of the vessels on the CIP skid to the user, the other vessel on the CIP skid can prepare the acid rinse solution.

Read the article for specific examples of physical and procedural models for fixed and portable CIP skids.

Understanding the jargon around batch processes begins with understanding the ISA88 terminology. Finding and reading articles like this is a good start as is the ISA website’s ISA88 page.